1. Field of the Invention
The present invention generally relates to wireless communications and, more particularly, to wireless communication devices that are hearing aid compatible.
2. Background of the Invention
Mobile stations, such as mobile telephones, cordless telephones, personal digital assistants (PDAs) and other wireless communication devices, transmit and receive RF signals from their antennas to support wireless communications. Typically, such RF signals are transmitted in the upper MHz and lower GHz frequency spectrums. In addition, such devices also produce electromagnetic noise, which is caused by operation of components within the station, such as backlighting, color displays, etc. The electromagnetic noise generally includes noise components both in the RF frequency range and at frequencies in the lower kHz and Hz frequency ranges (e.g. 100 Hz).
While the hearing aid industry has made progress in hardening the hearing aids against RF noise, audio transducers within the hearing aids are still susceptible to noise in the form of low frequency magnetic fields. Inasmuch as the audio transducers typically include telecoil couplers that receive signals via an induction field generated by an induction coupler, the low frequency magnetic field noise sometimes exists in the same frequency band as the generated induction field. This noise couples to the telecoil couplers, thereby degrading their signal quality.